feat(mcp): assemble the 8-tool toolkit with capability gating, proven via real dispatch

Also fixes async-test DB isolation: test_mcp_toolkit.py drives real MCP
dispatch, which runs tool functions' ORM calls on a sync_to_async worker
thread outside pytest-django's per-test atomic transaction, so writes
committed there weren't rolled back and leaked into later tests. Sets
DJANGO_ALLOW_ASYNC_UNSAFE for the async ORM setup calls and flushes the
Printer table after this file's tests via conftest.py.

tests/settings.py

@@ -1,4 +1,16 @@
 """Minimal Django settings for running bambu_run's pytest suite (in-memory SQLite)."""
+import os
+
+# test_mcp_toolkit.py drives real MCP dispatch through `mcp.client.Client`,
+# which runs the test body on the asyncio event loop (via pytest-anyio) while
+# still using plain synchronous Django ORM calls (Printer.objects.create(),
+# and the ORM calls inside the tool functions themselves). Django's asyncio
+# safety net treats any sync ORM call made while an event loop is running as
+# unsafe by default. It's genuinely safe here: sqlite is in-memory, tests run
+# single-threaded, and there's no concurrent request interleaving to corrupt
+# a shared connection. Set at settings-import time (before any test body
+# runs) rather than per-test, since Django reads this env var at call time.
+os.environ.setdefault("DJANGO_ALLOW_ASYNC_UNSAFE", "1")
 
 SECRET_KEY = "test-secret-key"